CVE-2021-1767
📋 TL;DR
A heap corruption vulnerability in Apple's image processing libraries allows attackers to execute arbitrary code by tricking users into opening maliciously crafted image files. This affects macOS, iOS, and iPadOS users who process untrusted images. Successful exploitation could lead to full system compromise.
💻 Affected Systems
- macOS
- iOS
- iPadOS
📦 What is this software?
Ipados by Apple
Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with kernel privileges leading to complete system takeover, data theft, and persistent backdoor installation.
Likely Case
Application crash leading to denial of service, or limited code execution within the sandboxed context of the affected application.
If Mitigated
No impact if systems are fully patched or if image processing is restricted to trusted sources.
🎯 Exploit Status
Exploitation requires user interaction to open malicious image. No public exploit code is known, but heap corruption vulnerabilities are often weaponized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4, iPadOS 14.4
Vendor Advisory: https://support.apple.com/en-us/HT212146
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available updates. 3. Restart the device when prompted.
🔧 Temporary Workarounds
Restrict image processing
allConfigure applications to only process images from trusted sources and disable automatic image loading.
🧯 If You Can't Patch
- Implement application whitelisting to prevent execution of unauthorized applications
- Use network segmentation to isolate vulnerable systems and restrict internet access
🔍 How to Verify
Check if Vulnerable:
Check macOS version: sw_vers -productVersion. Check iOS/iPadOS version: Settings > General > About > Version.Check Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Check in Settings appVerify Fix Applied:
Verify version is equal to or greater than patched versions listed in fix_official.patch_version.📡 Detection & Monitoring
Log Indicators:
- Application crashes related to image processing libraries
- Unexpected process creation from image viewing applications
Network Indicators:
- Downloads of suspicious image files from untrusted sources
SIEM Query:
source="*application.log" AND ("crash" OR "segfault") AND ("image" OR "CG" OR "CoreGraphics")